1. Field of the Invention
This invention relates to a process for preparing elastomeric molded parts having urethane groups or urethane and urea groups and to the elastomeric molded parts prepared thereby. Conventional ingredients are used to prepare the molded parts except for the polyhydroxyl compounds used.
2. Description of the Prior Art
The preparation of cross-linked plastics according to the isocyanate-polyaddition method is known. German Application No. 11 96 864 (U.S. Pat. No. 3,099,516) discloses that hydroxyl group-containing compounds and polyisocyanates are foamed for this purpose in the presence of blowing agents and catalysts. With a suitable choice of the ingredients flexible and rigid polyurethane elastomers as well as all intermediate modifications can be produced.
Elastomeric molded parts having urethane and optionally urea groups have satisfactory to very good mechanical properties. The dull surface of the molded parts on the other hand is not satisfactory. Particularly unsatisfactory is the light fastness and weather resistance which can be improved by adding expensive stabilizers on a short-term basis only since the stabilizers only delay the decomposition reactions.